It is known that pumps of this type are commonly used in the mining or petroleum industry for pumping heavy liquids such as petroleum, liquid slurries, fracturation fluids and the like. Pumps of this type are usually large in size and designed to discharge liquids at a high flow rate under high pressure, usually more than 200 bars.
In the particular case of petroleum operations, it is also necessary for a pump of this type to be relatively small in size, sufficiently so to allow it to be loaded and transported on a truck along with its drive motor. Therefore, it is understandable that the trend is to reduce the weight and overall size of the pump while increasing its liquid discharge pressure. Solutions known to date (and described for example in Girodin and Pere U.S. Pat. Nos. 4,106,354, 4,513,630, as well as in French specification Nos. 885,831 to Lefftz and 2,271,459 to Creusot-Loire) consist in using a barrel-type piston pump with the piston linkage controlled from a rotating inclined plane, the rotating inclined plane resting on thrust bearings at the bottom of the pump housing, which encloses the linkage.
In practice, it is reported that this known technique has a serious disadvantage. In fact, the pump external housing transmits the thrust forces between the rear thrust bearings of the rotating oscillating plate and the barrel into whose cylinders the liquid is discharged by the pistons. In other words, the higher the discharge pressure, the greater the stresses transmitted by the housing, thus requiring a large and heavy housing. The pumps now known have thus reached a limit beyond which it is impossible to increase the liquid pressure without increasing the weight and size of the pump and drive motor assembly, which then becomes quite impossible to transport by truck.
French specification No. 2,572,774 to the present applicant has taught an embodiment preventing some of these disadvantages by having a rotating machine with a barrel and a rotating inclined plane supplied with a new type of linkage making it possible to increase the liquid discharge pressure while reducing the overall weight of the pump and drive motor assembly.
A rotating machine according to French specification No. 2,572,774 to the present applicant and U.S. Pat. No. 4,106,354 to Girodin contains a fixed barrel having cylindrical bores into which run discharge pistons, each of which is connected by a rod to an inclined plane with an oscillatory tacking movement, whose rear surface is equipped with a drive journal perpendicular to the front thrust surface of the plate. The plate has a spherical bearing whose circular meridian forms a center angle of at least 180.degree., while inside the spherical bearing is a fixed spherical pivot solidary with an arm anchored axially in the center of the barrel, so that the thrust of the plate during operation is transmitted directly to the barrel through the spherical bearing which makes a pulling action, without involving the strength of the housing walls, particularly in the rear portion.